This invention relates generally to magnetic resonance imaging (MRI) systems and more particularly concerns minimizing the noise and/or vibrations generated by an MRI system using secondary vibrational inputs.
MRI systems require a uniform magnetic field and radio frequency radiation to cause magnetic resonance in the atomic nuclei of the subject being imaged. The magnetic resonance of the nuclei provides information from which an image of the portion of the subject containing these nuclei may be constructed. The magnetic field, which must be highly homogeneous, can be generated by a large permanent or superconducting magnet. The RF radiation is generated by an RF coil situated within the magnetic field. Magnetic field gradient coils are used to encode spatial information into the image signal. Typically, these elements are arranged so as to be contained within a structure having a cylindrical bore with a diameter large enough that the subject being imaged can be placed within the cylinder. A more complete discussion of MR imaging may be found in U.S. Pat. No. 4,471,306 assigned to the same assignee as the present invention.
Magnetic resonance imaging is now a widely accepted medical diagnostic procedure and its use is becoming increasingly popular. However, the acoustic noise levels generated by current MRI systems approach 100 decibels. These high noise levels can cause a substantial degree of patient discomfort and often require a test to be aborted prior to completion. MRI technology is not available to some patients only because they are unable to cope with the MRI environment. Noise is also a major concern for staff members operating the devices.